Consider this reaction: 2al(s) + 3 cucl2(aq) → 2alcl3(aq) + 3 cu(s) if the concentration of cucl2 drops from 1.000 m to 0.655 m in the first 30.0 s of the reaction, what is the average rate of reaction over this time interval?

The average rate of reaction over a given interval can be calculated by taking the difference of concentration on a particular given reactant, and dividing it by the total time. In this case, (1.00 M - 0.655 M)/30 s = 0.0115 M/s, or 0.0115 mol/L-s, and this is the final rate of reaction.